Transducer units are frequently fabricated from one or more piezoelectric ceramic elements having metallic electrodes bonded thereto. Th resulting structure has electrical capacity which is commonly turned by an external inductor to provide the desired electrical resonance characteristic to the transducer assembly. The combination of the mechanical vibrational characteristics and the electrical resonance provide the overall frequency band-pass characteristic in converting sonic energy incident upon the transducer assembly to electrical energy, as well as in converting electrical energy into acoustic energy.
A problem arises in that the mechanical portions of the transducer assembly must be sufficiently large to impart the desired mechanical vibrational characteristic to the transducer assembly. In addition, the inductive element utilized in tuning the capacitance of the transducer assembly is often comparable in magnitude to the physical size of a mechanical component of the transducer assembly such as a rear member or the ceramic transducer unit. Thus, the transducer assembly with the inductive tuning element has greater size and weight than may be necessary.